1. Field of the Invention
The present invention relates to a camera in which a lens cap is detachably mounted.
2. Description of the Related Art
Hitherto, for the purpose of protection of a photographic lens and prevention of dirt, when a camera is not used, a lens cap is mounted on the front of the camera.
In case of a camera having a detachable lens cap and in addition a finder as well as a photographic lens, it is impossible through the finder to confirm as to whether the lens cap is mounted. Thus, there is a possibility that the photographic operation is performed while the lens cap is attached and thus an operational error will occur.
In order to prevent such an operational error, it is considered that a camera is provided with a lens cap which covers a photographic lens and a finder as well. However, in this case, there is a need to cover the finder located apart from the photographic lens. Thus, it is necessary to provide a large size and unusual configuration of lens cap. A large size of lens cap is inconvenient in treatment, and a unusual configuration of lens cap brings about a problem in design.
Japanese Patent application Laid-Open Gazette No. Hei.9-105974 discloses such a technology that a lens cap for covering an optical system for focusing is provided together with a photographic lens, and it is determined as to whether the lens cap is mounted in accordance with a luminance level measured by a photo-electric element, or a photocell for focussing and a luminance level measured by a photo-electric element, or a photocell for focussing, which is not covered by the lens cap, and an alarm is generated. However, it is necessary also for the lens cap disclosed in Japanese Patent application Laid-Open Gazette No. Hei.9-105974 to cover the optical system for focusing as well as the photographic lens. Thus, it is necessary to prepare a large size and unusual configuration of lens cap. Accordingly, this technology is also associated with the problem of inconvenience on a treatment of the lens cap and the problem on a design.
Further, Japanese Utility Model Application Laid-open Gazette No. Sho.60-98973 discloses a technique for detecting a lens cap by a switch. In case of detecting the lens cap by a switch, however, a specific shape of lens cap has to be used to detect the lens cap in order that when the lens cap is attached, the switch is reliably operated. In the event that a photographic filter is attached to the front of a lens barrel, some structure of the switch is associated with such a fear that the photographic filter is erroneously detected as the lens cap.
Japanese Patent application Laid-Open Gazette No. Hei.2-247627 also discloses a technology for detecting a lens cap by a switch. However, Japanese Patent application Laid-Open Gazette No. Hei.2-247627 fails to disclose the use of a detection unit, and it is considered that such a technology is associated with a fault similar to that of Japanese Utility Model Application Laid-open Gazette No. Sho.60-98973.
In order to prevent an error of a photography, it is considered that a camera incorporates thereinto a lens cap which opens in accordance with an operation always necessary for the photography, for instance, an operation for turning on the power switch. However, in some structure of the photographic lens, it often happens that it is difficult to incorporate thereinto such a lens cap.